Vicinal toluenediamine mixtures

ABSTRACT

Toluenediamine mixtures comprising at least about 96 percent by weight of vicinal toluenediamine isomers and not more than about 4 percent by weight of nonvicinal isomers, said mixtures being adapted for conversion to bz-methyl-1-H-benzotriazoles in high yields.

United States Patent Spatz et al. 1 Jan. 25, 1972 [54] VICINALTOLUENEDIAMINE [56] References Cited MIXTURES UNITED STATES PATENTS [72]Inventors: Sydney M. Spitz, Williamsville; Maurice E 'flky, orchardPark; Francis E. Evms, 2,853,467 9/1958 Bloom et al ..260/47 Hamburg aofNX' 3,246,035 4/l966 Forman et al... ..260/578 3,413,350 [1/1968 Crosset al. ..260/578 [73] Assignee: Allied Chemical Corporation, New York,3,414,619 12/1968 Cross at al... ..260/578 NY. 3,420,752 1/1969 Kirss etal. ..260/582 [22] Filed: June Primary Examiner-Richard D. Lovering [2]]App]. No.: 835,257 Assistant Examiner-Irwin Gluck Attorney-Ernest A.Polin [52] [1.8. CI ..252/l82, 252/390, 252/401, [57] ABSTRACT 260/47EN, 260/578, 260/582 [511 lnt.Cl ..C07c 87/48 Toluencdiamine mixturesmpri ing at le st about 96 er- [58] Field oiSearch ..252 182, 390,401;260/578, cm y weight of viciml tOhwmxiiamine isomers and not260/582, 47 EP, 348 more than about 4 percent by weight of nonvicinalisomers,

said mixtures being adapted for conversion to bz-methyl-l-H-benzotriazoles in high yields.

3 Claims, No Drawings VICINAL TOLUENEDIAMINE MIXTURES VlClNALTOLUENEDIAMINE MIXTURES The present invention relates to vicinalaromatic diamine mixtures. More particularly it relates to mixtures ofvicinal toluenediamines which are suitable for conversion tobzmethyl-l-H-benzotriazoles in high yields.

Vicinal toluenediamines, sometimes called orthotoluenediamines, and morespecifically l-methyl-2,3- and 1- methyl-3,4-phenylene diarnines, areprecursors of bz-methyll-H-benzotriazoles, i.e., 4- andS-methyl-l-H-benzotriazoles, which are valuable tarnish and corrosioninhibitors. in the past, conversions of individual vicinaltoluenediamines to the corresponding -methyl benzotriazoles in theconventional manner, as by low temperature diazotizations at betweenabout C. and C. followed by ring closure at elevated temperatures ofabove about 50 C., have afforded yields of the triazole of no more thanabout 68 percent of theory, even when individual vicinal isomers ofpurities over 99 percent are used. Moreover, such individual isomers,even when they contain only a small fraction of a percent of nonvicinalisomers produce considerably tarry byproduct, for example as high asabout 30 percent or more based on the weight of the triazole product.

A prior art expedient for improving product yield in the foregoingconventional syntheses, which prescribes both diazotization andcyclization at elevated temperature, requires impractically slow mixingof the reactants and generally entails addition of antioxidant toprotect the labile vicinal diamine.

Vicinal toluenediamine mixtures are byproducts of the manufacture ofnonvicinal toluenediamines by reduction of dinitrated toluene, asdescribed in US. Pat. No. 3,420,752, granted .Ian. 7, 1969, and areseparable therefrom by fractional distillation. However, such prior artvicinal diamine mixtures contain no more than about 90 percent orthoisomers, usually between about 70 percent and about 90 percent orthoisomers, the remainder predominantly nonvicinal toluenediamines. We havefound that these mixtures, when subjected to the above conventionaltechniques, produce unacceptably low conversions to methylbenzotriazoles. The reason for such low conversions is not clearlyunderstood since even vicinal toluenediamine distillates of reduceddinitrotoluene which contain as much as about 90 weight percent vicinaltoluenediamines, and even similar mixtures containing as much as about95 weight percent vicinal isomers, give a product yield in theneighborhood of only about 60 percent of theory and give rise toextensive formation of byproduct which appears as a tar. Moreover,methyl benzotriazoles, as conventionally prepared from such diaminemixtures, contain a colored contaminant which cannot be removed byrecrystallization. Such discoloration precludes use of the product inmany application, e.g., in household detergents.

It is an object of the present invention to provide a mixture of vicinaltoluenediamines suitable for conversion to bzmethyl-l-H-benzotriazolesin high yields of at least about 70 percent of theory and free ofobjectionable colored contaminants.

This and other objects and advantages are accomplished according to ourinvention by providing a mixture of 2,3- toluenediamine and3,4-toluenediamine containing total vicinal toluenediamines of at leastabout 96 percent by weight and not more than about 4 percent by weightof nonvicinal toluenediamines, said mixtures containing2,3-toluenediamine in amounts sufl'rcient to provide a ratio of 2,3- to3,4- toluenediamine between about 0.3:1 and. about 1 .5: 1.

We have found, surprisingly, that when mixtures of vicinaltoluenediamines of the purity and compositions described above aresubjected to conventional diazotization and cyclization, the diamines ofthe invention afford mixtures of 4- and 5 methyl-1-l-l-benzotriaaoles inyields which are about 30-30 percent greater than those produced incomparable reactions LII of mixtures of lesser proportions of vicinaltoluenediamines and are at least equivalent to yields obtained withindividual vicinal toluenediamines of over 99 percent purity. Yieldsfrom mixtures of the vicinal toluenediamines of the invention, moreover,are 10-20 percent greater than those produced in comparable reactions ofindividual toluenediamines of similar vicinal toluenediamine content.The amount of high molecular weight side product obtained on conversionof the present novel vicinal diamine mixtures to benzotriazoles isunexpectedly small, decreasing as the proportion of nonvicinaltoluenediamines decreases. It is thus apparent that the mixtures of 2,3-and BIA-toluenediamines in the proportions prescribed by the inventionpromote methyl benzotriazole formation whereas contamination of thediamine mixtures with higher proportions of nonvicinal,toluenendiaminesinhibits benzotriazole formation.

The vicinal toluenediamine mixtures of the invention can be prepared byany suitable procedure. They can be prepared, for example, by blendingmolten 2,3- and 3,4-toluenediamines in the proportions prescribed by theinvention. More economically, the novel mixtures are obtained from thereduced aromatic dinitration product of toluene, for example byfractional distillation of the resulting toluenediamine mixtures atreflux ratios greater than about 50:1. An especially efficientproduction of the novel diamine mixtures is achieved by fractionaldistillation of the aforementioned vicinal toluenediamine distillatesobtained as described in US. Pat. No. 3,420,752, employing adistillation column of about 15 to 30 or more theoretical plates, astill head temperature and pressure of about l50-180 C. and 20-60 mm.Hg, respectively, and a reflux ratio of about 3:1 to 10:1 or greater.

Conversion of the vicinal toluenediamines to the corresponding methylbenzotriazoles proceeds as illustrated below:

5-methylbenzotriazole NH2 HONO NHz 2,3-toluenediamine and HONO '3,4-toluenediamine Vicinal toluenediamine mixtures of the inventionsuitable for conversion to methyl benzotriazoles in yields of about 70percent of theory or higher should contain at least about 96 percent byweight of vicinal toluenediamines and should contain 2,3- and3,4-toluenediamines in weight ratios between about 03:1 and 15:1, morepreferably between about 0.621 and 12:1 and especially between about0.65:1 to 0.85:1. The amount of nonvicinal toluenediamine in suchmixtures should be no more than about 4 percent by weight. Vicinaltoluenediamine mixtures of the invention containing about 96 percent byweight of vicinal toluenediamines provide yields of methylbenzotriazolesat least as high as those of highly pure, i.e., over 99 percent pure,individual vicinal toluenediamines, and no greater tar formation thanobtained with such highly pure individual vicinal toluenediamines. Suchmixtures also yield products having an off-white color, acceptable formost purposes such as epoxy resin curing. Mixtures containing about 98percent by weight of vicinal toluenediamines provide yields of aboutpercent of theory and substantially less tar than the highly pureindividual isomers and thus give an additional advantage. Mixturescontaining at least about 99.5 percent by weight of vicinaltoluenediamines and not more than about 0.5 percent by weight ofnonvicinal toluenediamines are especially preferred since they providemethylbenzotriazoles in yields of about 90 percent or more havingextremely low tar contents. Such methylbenzotriazoles are substantiallycolorless after recrystallization and, hence, are eminently suitable foruse in household detergents.

The vicinal toluenediamine mixtures of the invention are effective inhardening (i.e., curing) liquid epoxy resin-forming compositions (suchas the diglycicyl ether of bisphenol A) to resins having an excellentdegree of cross-linking. Curing of epoxy resins employing the diaminecompositions of the invention if effected in an essentially conventionalmanner, as disclosed in H. Lee and K. Neville Handbook of Epoxy Resins,McGraw-Hill Book Co., New York, N.Y. 1967, Chapter 8.

1n the following examples which illustrate our invention, parts,percentages and proportions are by weight, unless otherwise noted, andtemperatures are in degrees centigrade.

EXAMPLE 1 Production of Pure Vicinal Toluenediamines From a Mixture Highin Ortho lsomers A still equipped with a 40-plate Oldershaw column(l-inch diameter; 21 to 22 theoretical plates) is charged with about3,991 parts of a vicinal and nonvicinal toluenediamine mixture(distilled from the reduced aromatic dinitration product of toluene inaccordance with U.S. Pat. No. 3,420,752) having the followingcomposition:

72.4 percent 2,3- and 3,4-toluenediamines 0.63 percent2,5-toluenediamine 25.85 percent 2,4- and 2,6-to1uenediamines 1.03percent lites" (i.e., compounds more volatile than the foregoingtoluenediamine isomers) This mixture is distilled at a reflux ratio ofabout 10:] to remove a distillation forecut (237 parts) containing thelites" (collected at a still head temperature and pressure of l l6l7 2and 48-50 mm. Hg, respectively, and a still bottom temperature andpressure of 135-195 and 8487 mm. Hg, respectively. The reflux ratio isadjusted to about 5:1 and 1,838 parts of distillate is collected at astill head temperature and pressure of 172-173 and 4950 mm. Hg,respectively and a still bottom temperature and pressure of 195202 and8690 mm. Hg, respectively. The distilled product which is a solid (mp.of about 56-64) contains about 99.97 percent vicinal toluenediamines,i.e., 2,3-toluenediamine and 3,4- toluenediamine, the isomers beingpresent in proportions of 2,3- to 3,4-isomers in the range of about0.3:] and 1.5:1 and containing no more than 0.03 percent nonvicinaltoluenediamines, i.e., 2,4; 2,5-; 2,6-toluenediamines.

EXAMPLE 2 Production of Pure Vicinal Toluenediamines From a Mixture Lowin Ortho lsomers A mixture containing isomeric toluenediamines, 1.11percent 2,3-; 2.06 percent 3,4-; 0.31 percent 2,5-; 21.8 percent 2,6-and 74.7 percent 2,4-isomers, corresponding to about 3.2 percent vicinaltoluenediamines and 96.8 percent nonvicinal toluenediamines, obtained byreduction of the aromatic dinitration product of toluene is continuouslydistilled to recover a nonvicinal toluenediamine distilland followingthe procedure of U.S. Pat. No. 3,420,752, but employing a reflux ratioin the range of about 50:1 to about 60:1, i.e., a reflux ratio greaterthan that prescribed in the aforementioned patent. A sample (about 450parts distillate) collected at a still head temperature and pressure ofabout 158 and 24 mm. Hg, respectively; a still bottom (i.e., reboiler)temperature and pressure of 214 and 80 mm. Hg, respectively, a stillfeed rate of 2.04Xl0 parts per hour and a distillate recovery rate of4.77X10 parts per hour) has the following composition:

40.4 percent 2,3-toluenediamine 59.2 percent 3,4-toluenediamine 0.4percent 2,4-toluenediamine a trace 2,6-toluenediamine (i.e., 99.6percent vicinal toluenediamines, in the proportion of 0.68 of 2,3-isomerto 1.0 of 3,4-isomer, and about 0.4 percent nonvicinal toluenediamines.)

EXAMPLE 3 Production of a Mixture of 4- and 5-methyl-l -H-benzotriazoles (MBT) From a Mixture of 2,3- and 3,4-

toluenediamines A slurry of 244 parts (containing 243 parts, 1.99 molsvicinal toluenediamines) of the toluenediamine distillate of example 2(containing 99.6 percent vicinal toluenediamines) in a mixture of 240parts glacial acetic acid and 600 parts of water is agitated at 4050 todissolve the diamine mixture. The resultant solution is cooled to about5 and charged rapidly to a solution of 154 parts (2.18 mols) sodiumnitrite in 240 parts water. The temperature of the diazotized mass isallowed to rise to 90. The reaction mixture is then agitated for about 1hour while being allowed to cool to 40. The cooled mass is allowed tostand at ambient temperature (ca 25) for about 16 hours. The aqueousacetic acid layer which separates on standing is decanted and extractedwith 37.2 parts chloroform. The chloroform extract is washed byextraction with three 500 part portions of water and then distilled atatmospheric pressure to recover chloroform. The resultant distilland isdistilled at a still head temperature of 182-187; a still bottomtemperature of 207-23 1 and still head pressure of 3 mm. Hg, to recover243 parts of crude product as distillate and 5 parts of distillationresidue (a reddish brown tarry reaction byproduct corresponding to only2.04 percent of the distilled crude product). The reddish yellow crudeis recrystallized from 580.8 parts of benzene, dried in vacuo at ambienttemperature for about 16 hours and finally dried at 4550 in vacuo. Theresultant product (242 parts, 91.5 percent of theory based on vicinaltoluenediamine) charged is a white solid mixture of 4- andS-methyl-l-H-benzotriazoles (m.p. 7348).

EXAMPLE 4 The procedure of example 3 is repeated substantially asdescribed employing the vicinal toluenediamine distillate of example 1(containing 99.9 percent vicinal toluenediamines). On distillation ofthe chloroform-extracted organic layer of the reaction mixture, 240parts of distilled crude product are recovered together with 8 partsnonvolatile residue (corresponding to only 3.33 percent of the distilledcrude product). On recrystallization of the crude from 652 parts ofbenzene, 239 parts (90 percent yield of theory) of a mixture of 4- and5-methyl-1-H-benzotriazoles (a white solid, mp. 7475) is obtained.

EXAMPLE 5 When a mixture containing 98.0 percent vicinal and 2.0 percentnonvicinal toluenediamines is treated as described in example 3 above,an percent yield of theory, based on vicinal toluenediamine charged, ofan off-white mixture of 4- and 5-methyl-l-H-benzotriazoles (m.p. 7 1-73)is obtained.

EXAMPLE 6 When a mixture containing 96.6 percent vicinal and 3.4 percentnonvicinal toluenediamines is treated as described in example 3 above, a70 percent yield of theory based on vicinal toluenediamine charged of anoff-white solid mixture of 4- and 5-methyl-1-H-benzotriazoles (m.p.7274) is obtained.

EXAMPLE 7 The following comparative example illustrates theunsatisfactory production of bz-methyll -H-benzotriazoles from a vicinaltoluenediamine mixture containing about 4.7 percent nonvicinaltoluenediamines which is obtained from the reduction product of thearomatic dinitration of toluene.

A vicinal toluenediamine mixture of the following composi tion 39.6percent 2,3-toluenediamine 55.6 percent 3,4-toluenediamine about 60 andblended with 26.1 parts (0.138 equivalents) ofa liquid diglycidyl etherof Bisphenol A (Epon 828) and allowed to stand in water bath maintainedat 60il. The mass solidifies to an excellent epoxy resin in about 96 toI56 minutes, the

1.3 percent 2,6-toluenediamine 5 maximum temperature of the mixture atgelation being about 3.4 percent 2,4-toluenediamine 84.

(i.e., 95.2 percent vicinal and 4.7 percent nonvicinal PART B-Four bars(A inch X A inch X 4 inches) of cured toluenediamine) epoxy resin areprepared by blending Bisphenol A diglycidyl is treated substantially asdescribed in example 3 above. The ether with vicinal toluenediaminemixture as described in part results of this experiment are comparedwith those of exam- A and heating the liquid mixture in suitable moldsfor 3 hours ples 3 and 4 in the table below. at 90 and, subsequently,for 4 hours at l50.

The mean heat deflection temperature of the samples is EXAMPLE 8 163 (asdetermined at 264 psi. fiberstress according to the procedure of ASTMD648-56, I965 Book of ASTM Stan- The following comparative exampleillustrates the relatively l5 d d A i S i f T i and M ateriak Philadel.10W W of y Produced from phia, Pa., Part 27, pp. 208-2l 1) indicating anexcellent degree stantially P r 3,4-t0lu6fledlammeof cross-linking inthe cured resin.

The procedure of example 3 is repeated substantially as w l i describedin treating Parts of I. Toluenediamine mixtures comprising at leastabout 96 toluenediamine Containing at least 995 P of percent by weightof vicinal toluenediamines consisting of 2,3- toluenediamine, as n y ynuclear g resonance toluenediamine and 3,4-t0luenediamine, in a weightratio of spectra, dissolved in 72.3 parts glacial acetic acid and 90parts 23. [0 3,4-t l enediamine between about 03:1 a d b t water, with asolution of about 4 parts (0.57 m l Sodium l.5:l and containing not morethan about 4 percent by weight nitrite in 65 parts water. The results ofthis experiment are of nonvicinal toluenediamines. compared with thoseof examples 3 and 4 in the table below. 2. The toluenediamine mixture ofclaim 1 wherein the TABLE Yield of i'eerystallize d Distillation residueproduct (MBT) based an Ex. Toluenediamine charged Distilled crudeproduct (reaction byproduet) vicinal diamine charged 3 99.6% vicinal,0.4% non-vicinal toluenediamines 243 parts of reddish yellow 5 parts ofreddish brown tar 91.5% of white solid, M.P.

obtained in Ex. 2 (244 parts containing 243 parts, solid. (2.02% ofdistilled crude 73-78 C. 1.99 mols, oi the vicinal isomers). product). 499.9% vicinal, 0.1% non-vicinal toluenediamines 240 parts of reddishyellow 8 parts of reddish brown tar 90% of white solid, M.P. obtained inExample 1 (244 parts, 2 mols vicinal solid. (3.33% of distilled crude74-67 C. toluenediam ines). product). 5 98.0% vicinal, 2.0% nonvicinaltoluenediamines 176.2 parts 01 reddish yel- 25.7 grams reddish brown 80%of ofi white solid,

low solid. tar (14.6% of distilled M.P. 7173 C. crude product). 6 96.6%vicinal, 3.4% non-vicinal tolueiiediamines 159.4 parts of reddish yel-46. 8 grams reddish brown 70% of ofi-white solid,

low solid. tar (29.3% of distilled M.P. 7274 C. crude product). 7 95.2%vicinal, 4.7% non-vicinal toluenediamines dis- 172 parts of reddish ycl-83 parts of reddish brown 61.3% of brown solid,

tilled from the reduced product of the dinitratioii low solid. tar(48.8% of distilled M.P. 6970 C. of toluene (256.3 parts contaaining 244parts, 2 mols crude product). of the vicinal diamines. 8*3,4toluenediamine (36.6 parts, containing at least 27 parts of yellowsolid 8 parts of reddish borwn 68% of white solid, M.P.

99.5%, 0.298 mol, of the 3,4 isomer.

tar (29.6% of distilled crude product).

Comparable results are obtained with 2,3-toluenediamine containing atleast 99.5% 2,3-toluenediamine as with 3,4-tolucnediamine.

EXAMPLE 9 Epoxy Resin Curing with Vicinal Toluenediamines PART AAvicinal toluenediamine mixture (3.9 parts, 0.0638 equivalents) which isobtained according to the procedure of example 1 above and containsabout 99.88 percent vicinal toluenediamines; 0.046 percent nonvicinaltoluenediamines and about 0.073 percent lites is melted at

2. The toluenediamine mixture of claim 1 wherein the vicinaltoluenediamines comprise at least about 98 percent by weight of themixture and nonvicinal toluenediamines comprise no more than about 2percent by weight of the mixture.
 3. The toluenediamine mixture of claim1 wherein the vicinal toluenediamines comprise at least about 99.5percent by weight of the mixture and nonvicinal toluenediamines compriseno more than about 0.5 percent by weight of the mixture.